Abstract Our UCLA team in partnership with United Healthcare (UHC) proposes to form a cooperative agreement with the CDC to evaluate an innovative health system-based insurance product called the Diabetes Health Plan (DHP). This disease specific health plan offers preventive treatments and services with established efficacy at very low or no cost to patients with pre-diabetes and diabetes. The 2010 implementation of the DHP, by one of the largest for-profit insurance companies with employer groups in all 50 states, represents a unique and valuable opportunity for evaluation of a real-world system-level intervention. The overall goal of the research is to implement a rigorous empirical evaluation of the behavioral, economic, and health consequences of the DHP designed to prevent diabetes and/or prevent medium-term complications for persons with diabetes. We plan to conduct one primary effectiveness study (Aim 2) and three ancillary studies (Aims 3a, 3b and 4). Our specific aims are as follows: 1) To develop recruitment materials to increase participation by the most vulnerable patients with pre- diabetes or diabetes, and to track implementation and participation rates with the RE-AIM framework. 2) To determine whether participation in the DHP compared to coverage with the standard health benefit is associated with: a) Lower rates of progression to diabetes, among patients with pre-diabetes; b) Better control of cardiovascular risk factors, among patients with diabetes; c) Better adherence to diabetes- specific preventive services, among patients with diabetes 3) To determine whether participation in the DHP compared to coverage with the standard health benefit is associated with: a) Lower total costs (patient + health plan), among patients with pre-diabetes; b) Lower total costs (patient + health plan), among patients with diabetes 4) To determine whether patients with pre-diabetes who elect to participate in the UHC DPP/YMCA program versus those who elect to take metformin have different rates of progression to diabetes. 5) To fully participate in a multi-center network designed to facilitate collaboration, to examine the impact of multi-regional or national system and community policy changes, and to participate in development of the study wide protocol along with a core set of common metrics and measures, and analytic approaches. The UCLA team will use quasi experimental designs, de-identified data from UHC, and state of the art modeling strategies to adjust for selection effects in order to address these specific aims. In summary, the UCLA team's longstanding research partnership with UHC offers an important opportunity to understand whether the DHP leads to better health outcomes for patients. As evidenced by UCLA's performance in TRIAD, we believe that we are a highly collaborative and diverse group of researchers who, if selected, will also make important contributions to the Multi-Center Network proposed in this FOA.